The novel feature of the present invention is that it relates to a portable hot-press for thermowelding marked and/or printed foils of thermoplastic synthetic material, particularly PVC, to produce single-sheet identification cards. It includes a press drive, one fixed and one sliding cross bar of the press, and a fan for cooling the heating plates and the thermowelded foils. A hot-press of the kind mentioned, as it is known e.g. from German Utility Patent DE-GM No. 80 11 833, has a press stand with a fixed and a sliding cross bar to take the two heating plates. The sliding cross bar of the press is moved by a hydraulic cylinder, located centrally relative to four guide columns.
It was found that, when such a hot-press is in use, the sliding bar of the press tends to catch and become jammed if the state of friction between the four guide columns and the cross bar changes in an uneven manner.
However, since the state of friction with the respective guide columns does not remain constant over an extended period of operation, the sliding cross bar will again and again catch against the guide columns and become jammed, resulting in failure of the hot-press.